A more thorough explanation:

Jactus mercium navis levandae causa

Jactus mercium navis levandae causa is a Latin term that means "the throwing of goods into the sea for the purpose of lightening the ship." In Roman law, this is known as jettison. The lex Rhodia is the law that governs jettison.

Imagine a ship that is carrying too much weight and is in danger of sinking. To prevent this, the crew may need to throw some of the cargo overboard. This act of throwing cargo overboard is called jettison. The lex Rhodia requires that all consignors and the shipmaster share losses equally.

For example, if a ship is carrying 100 barrels of oil and needs to jettison 20 barrels to avoid sinking, the loss of those 20 barrels would be shared equally among all parties involved in the shipment of the oil.

Another example would be if a ship is carrying a variety of goods, including livestock. If the ship is in danger of sinking, the crew may need to jettison some of the livestock to lighten the load. The loss of the livestock would be shared equally among all parties involved in the shipment.

These examples illustrate how jettison works and how the lex Rhodia governs the distribution of losses among all parties involved in the shipment.